The following exceptional situations during task execution are covered by task actions:

• Input data fields contain faulty values: contractor may [Object to Task] indicating the respective fields.
• Task needs to be re-specified (different data fields, other input field values): requestor may [Withdraw Task Request].
• Output data fields contain faulty values: requestor may [Request Task Correction], contractor may [Withdraw Task Results].
• Other users are more suited for task execution: contractor or requestor may [Forward Task] to other users for execution.
• Contractor is not able or willing to execute the task: contractor may [Reject Task].
• Commitment to task execution needs to be revoked: contractor may [Uncommit to Task].
• Task execution is no longer necessary: requestor may [Cancel Task].